Bug 166944

Created attachment 298622 [details] Crash Log ASSERT_NOT_REACHED in Heap::endMarking seen on EWS bots Saw this on EWS output on bug 166862 from yesterday (1/10/2017). That bug does not appear to be related in any way. Attached the full crash from the bot. Unresolved visit races: 0x126ca2050(JSObject::visitButterfly) SHOULD NEVER BE REACHED /Volumes/Data/EWS/WebKit/Source/JavaScriptCore/heap/Heap.cpp(790) : void JSC::Heap::endMarking() 1 0x105627000 WTFCrash 2 0x104e8bcd5 JSC::Heap::endMarking() 3 0x104e8b466 JSC::Heap::markToFixpoint(double) 4 0x104e8e215 JSC::Heap::collectInThread() 5 0x104e9e179 JSC::Heap::Thread::work() 6 0x105634524 WTF::AutomaticThread::start(WTF::Locker<WTF::LockBase> const&)::$_0::operator()() const 7 0x1056342cd void std::__1::__invoke_void_return_wrapper<void>::__call<WTF::AutomaticThread::start(WTF::Locker<WTF::LockBase> const&)::$_0&>(WTF::AutomaticThread::start(WTF::Locker<WTF::LockBase> const&)::$_0&&&) 8 0x1056340bc std::__1::__function::__func<WTF::AutomaticThread::start(WTF::Locker<WTF::LockBase> const&)::$_0, std::__1::allocator<WTF::AutomaticThread::start(WTF::Locker<WTF::LockBase> const&)::$_0>, void ()>::operator()() 9 0x104c2b7ea std::__1::function<void ()>::operator()() const 10 0x1056a1ede WTF::threadEntryPoint(void*) 11 0x1056a3981 WTF::wtfThreadEntryPoint(void*) 12 0x7fff96cc599d _pthread_body 13 0x7fff96cc591a _pthread_body 14 0x7fff96cc3351 thread_start Appears to be this assert: void Heap::endMarking() { if (!m_visitRaces.isEmpty()) { dataLog("Unresolved visit races: ", listDump(m_visitRaces), "\n"); RELEASE_ASSERT_NOT_REACHED(); } ... }